I am making a jack-o'-lantern using a simple Automatic Dark detector..
For the Automatic Dark detector..
Things you require -
# 1 BC547 transistor
# 1 LDR
# 1 LED (any color of your choice)
I have used white LED for demo and Red LED for lantern
# a 100K resistor
# a 100R resistor
# a 9V Battery
and of course a breadboard
Insert BC547 transistor into breadboard
Connect emitter of transistor to negative supply of battery.
Connect one end of LDR to base of transistor and other to negative supply of battery.
Connect 100k resistor to the base of transistor and to positive end of supply.
Step 5: Almost Done...
Connect 100R resistor to positive end of supply and insert other end anywhere in breadboard. To this end connect the positive end of LED. Connect the negative terminal of LED to the collector lead of transistor.
Step 6: Supply the Circuit..
Connect the battery to the respective terminals on breadboard and observe the LED.
When light level on LDR decreases i.e. when surrounding is dark - the LED glows otherwise LED remains OFF.
Step 7: Automatic Dark Sensor Action
Step 8: Halloween Is Round the Corner...
After your Automatic Dark detector is ready you can use it for a cool and classic Jack-o'-lantern.For the lantern use simple cardboard cut outs. Cut out the pattern or any other design of your choice. Place your automatic detector inside the lantern and then wait for the night... Lantern will lit up when it's dark...pretty cool..huh??
Happy Halloween !!
Step 9: The Circuit on PCB..
I made the same circuit on PCB by soldering the elements I had used on breadboard and it works perfectly well.